Re: Linux mdadm superblock question.

From: Nick Bowler
Date: Thu Feb 18 2010 - 09:12:57 EST


On 04:33 Thu 18 Feb , Goswin von Brederlow wrote:
> Nick Bowler <nbowler@xxxxxxxxxxxxxxxx> writes:
>
> > On 09:41 Wed 17 Feb , david@xxxxxxx wrote:
> >> however for people who run systems that are known ahead of time and
> >> static (and who build their own kernels instead of just relying on the
> >> distro default kernel), all of this is unnessesary complication, which
> >> leaves more room for problems to creep in.
> >
> > Such people can easily construct an initramfs containing busybox and
> > mdadm with a shell script hardcoded to mount their root fs and run
> > switch_root. It's a ~10 minute jobbie that only needs to be done once.
>
> Except when mdadm, cryptsetup, lvm change you need to update it.
> Esspecially when you set up a new system that might have newer
> metadata.

I meant "once per system". One typically doesn't _need_ to update the
mdadm in the initramfs, as long as it's capable of assembling the root
array.

> Also at least Debian doesn't (yet) support a common initramfs for their
> kernel packaging. You either build a kernel without need for one or you
> have a per kernel initramfs that is automatically build and updated
> whenever anything in the initrmafs changes. Not often, but still too
> often, the initramfs then doesn't work.

The scenario was when users configure and build their own kernel. These
users are presumably capable of using grub's "initrd" command or the
CONFIG_INITRAMFS_SOURCE kernel option.

--
Nick Bowler, Elliptic Technologies (http://www.elliptictech.com/)
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